$\dfrac{2}{5} \div \dfrac{4}{5} = {?}$
Explanation: Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $\dfrac{4}{5}$ is $\dfrac{5}{4}$ Therefore: $ \dfrac{2}{5} \div \dfrac{4}{5} = \dfrac{2}{5} \times \dfrac{5}{4} $ $ \phantom{\dfrac{2}{5} \times \dfrac{5}{4}} = \dfrac{2 \times 5}{5 \times 4} $ $ \phantom{\dfrac{2}{5} \times \dfrac{5}{4}} = \dfrac{10}{20} $